Effective vaccines exist for many pathogens. But rational design methods have failed to generate vaccines against many important pathogens. Importantly, our understanding of the molecular pathways involved in generating long-lived and broadly protective immunity is incomplete. Using a newly discovered molecule, this application is directed at understanding pathways that regulate the ability of B cells to provide durable and cross-protective antibody responses. We have discovered that the transcription factor Zbtb20 is required for maintenance of long lived plasma cells, with only high affinity clones persisting afte immunization. These findings provide us with the unique opportunity to: 1) Identify the signaling and survival pathways that regulate plasma cell diversity and lifespan through genetic complementation experiments; 2) Determine the function of low and moderate affinity antibodies in cross-protection against viruses and in the pathogenesis of autoimmunity.